SparkFun Forums

[CAVU]

I'm ordering a Lidar to upgrade a sonar designed system.
I see that it works with either the wire library (with arduino) or i2c library but the former isn't recommended.
the supporting documents direct you (indirectly) to CSS after wadding through a lot of documents, registering with CSS (and their sending back my password back in an email) it's not clear what the library Sparkfun is recommending for Lidar.
Can you all check the links or just make it a direct github link to get the i2c library.
this might be a dumb question but why can't sparkfun just make the links available like adafruit and explain why it isn't recommended?

[MarkS]

I'm going to guess the answer is in this line: "'Arduino I2C Master Library' from DSS Circuits (a more sophisticated I2C library than the default Wire library)". Emphasis mine.

I do not use Arduino, but it would seem to me, from reading that, that the Arduino Wire Library is a basic i2C communications library, and does not support the full i2c specifications. Why this matters, I do not know.

[CAVU]

Thanks MarkS,
I'm sure you are right.
nice if they could make it a direct link to the library.

[CAVU]

Any update when the Lidar units will be in stock.

[Ross Robotics]

We wouldn't know that. We don't work for SFE. You can ask on the product comments.. Maybe an employee will see it.

[jbeale]

Anyone else have one of these Lidar-LITE units? I now have two, both from Sparkfun. The second one has a lens with a wavy, scalloped appearance which I think is on the inner surface, not the outer surface. Anyone else's look like that? Is it by design, or a defect? I don't think this kind of lens can focus very well.

[jbeale]

I notice the two LIDAR-Lite units i got from Sparkfun about a month apart, have different beam sizes. At a distance of 15 feet, the first unit I received has a FWHM beamwidth just over 1 inch, not counting a larger faint halo. The second unit which I just got has a beam around 3 inches wide at the same distance. Also, the laser collimating lens has a "scalloped" appearance on visual inspection that the first device did not have. They both do work, but the change in lens and beam pattern may mean they work differently, depending on your application.



Follow up: very casual test with the two units, with a white car parked across the street as a target, showed the second unit actually performed better despite the larger beam.

Unit 1: range min/avg/max: 1800, 1980, 2005 cm
Unit 2: range min/avg/max: 1976, 1984, 1991 cm

I probably didn't hit exactly the same spot, and with a shiny surface like a car the incident angle matters a lot. But I wiggled it around a bit and the numbers did not vary that much. Anyway, from one simple test the second unit was certainly not worse.

[jbeale]

UPDATE: received a communication from PulseLight3d. The "scalloped" appearance of the lens is an intentional design feature (diffuser) and in fact that is the reason the second unit works better than the first one. The first unit I received was missing the diffuser by accident.

[CAVU]

jbeale,
were you able to get the i2c library from CSS without difficulty.

[jbeale]

sorry for hijacking your thread about the i2c library. I did not try the CSS library, in fact I'm using it with a Teensy T3.1 board, and I'm using a modified Wire.cpp library I think is specific to that ARM-based platform. See also: https://forum.pjrc.com/threads/28036-Tr ... #post70213

[CAVU]

Thanks! let me know how your project works out.

[jbeale]

Just wanted to compare the two LIDAR-Lite units I have more carefully. I aimed them at the same point on a door about 5.8 meters away. The first unit I got (call it "bad") ranged mostly 575 cm, but occasionally reported 514 cm. The second unit I got reported around 578 cm and every reading in a set of 5000 readings was in the range 575..581 cm. The first unit is the one with the smaller spot size (apparently inadequate or missing diffuser). I used exactly the same code and same hardware (Teensy 3.1) to read out from both.

(Note: all of the too-low readings from "bad" unit #1 were exactly 514 cm, suggesting a digital rather than an analog problem. Since all my hardware and software was the same between the two units, I do not think the problem is on my end.)